1. Field of the Invention
The present invention is for a thrombectomy catheter, and more particularly, relates to a cross stream thrombectomy catheter with a flexible and expandable cage which is deployable and expandable about the distal region of the cross stream thrombectomy catheter for abrasive contact with and for abrasive removal of hardened thrombus or other foreign material in addition to and in cooperation with ablative cross stream flow. This device is used in the removal of tissues or highly organized, old thrombus in the most difficult of cases where simple water jet thrombectomy procedures may be ineffective.
2. Description of the Prior Art
Prior art thrombectomy catheters incorporating water jet technology encounter difficulty in dealing with old and difficult thrombus. Thrombus consistency can vary tremendously depending upon factors such as the age of the clot, conditions under which it was formed, the hematology of the patient and other factors. This is especially true in the case of deep vein thrombosis, where the thrombus can vary from fresh soft clot to older more organized clot. This more organized thrombus is the most difficult to remove. Furthermore, the large veins in the legs present the need to remove large volumes of clot that are not only larger in diameter but can extend for longer distances. In the case of lysins, the distances the chemical must diffuse is longer. This results in longer treatment times and hence more complications, such as hemorrhagic stroke. In the case of mechanical agitators, such as the Bacchus Trellis device, the device is limited in its operating diameter. If the device is designed to operate in a large diameter, the forces to operate the device would increase and the mechanical integrity of the agitator would need to increase (i.e., diameter of the wire) and grow larger, both of which make the device more difficult to deliver and operate. The use of the AngioJet®, a rheolytic cross stream thrombectomy catheter, includes an inherent ability to remove thrombus of larger diameter than the catheter's diameter. However, the disruptive strength of the device falls off with the radial distance from the catheter. Hence, at some radial distance the clot is stronger than the disruptive force generated by the AngioJet® cross stream flow patterns. In the case of organized thrombus, this radial distance from the catheter is smaller than for softer thrombus. The present invention adds another dimension to water jet thrombectomy by dealing with very difficult thrombus. Water jet thrombectomy procedures in general can be limited in ability, but adding mechanical disruption of difficult to remove thrombus to water jet ablation is actually taking thrombectomy procedures to another level. By combining mechanical agitation; i.e., abrasive intimate contact of thrombus by a flexible and expandable cage component, with a rheolytic thrombectomy catheter (AngioJet®), larger diameters of thrombus can be cleared than can be cleared by mechanical agitators or rheolytic cross stream thrombectomy catheters individually. This combination also extends to combining the use of the AngioJet® with lysins. By disrupting thrombus with flow, the lysins can be mixed better with the thrombus, and the lysins soften the clot such that AngioJet® is more effective. Furthermore, such a technique enables shorter treatment times compared to the use of either AngioJet® or lysins alone. Consequently, the combination of mechanical agitators with AngioJet® and even with lysins represents synergistic efficiencies in the removal of thrombus.